Ocean Energy Sources - Class IX

The energy potential from the sea (tidal energy, wave energy and
ocean thermal energy) is quite large, but efficient commercial exploitation
is difficult.

OCTEC stands for ocean thermal energy conversion power plant. It is a device used to harness tidal energy to produce electricity.

Tide  are the rise and fall of sea levels caused by the combined effects of gravitational forces exerted by the Moon, Sun and rotation of the Earth. The effect of moon is most prominent among all the factors. Rise of ocean level is called high tide and fall of ocean level is called low tide.

$71 %$ of the Earth's surface is covered by oceans. Hence, most of the solar energy is absorbed by the oceans. This energy can be harnessed using OCTEC. Hence, ocean thermal energy has great potential.

Energy from the sea can be classified into three types:

Temperature gradient of the water with deep ocean being cold and tropical surface water being warm due to the Sun's heat is the ocean thermal energy.

Dams or reservoirs are usually build near the narrow opening of the seashores to harness the energy of the waves during high tide in generation of electricity.

Waves are made to fall from a height on to the rotor of a turbine or dynamo to make them rotate. This mechanical energy is then converted to electrical energy.

The two different ways of harnessing energy from ocean is Tidal wave and Ocean Thermal Energy Conversion (OTEC).
Answer (A) Tidal Wave, OTEC

The hot water in the ocean is used to evaporate liquids like ammonia or CFC. This vapour is used to rotate the turbines of the generator and the vapour is again cooled down to a liquid by using the cold water from the ocean depth. This cooled liquid ammonia or CFC is again vapourised and the above process continues.

While tidal energy is a source of energy, it is not considered a 'major' source compared to other renewables due to limited suitable sites and high infrastructure costs.

OTEC stands for Ocean Thermal Energy Conversion, which specifically uses the temperature gradient between surface and deep ocean layers to generate electricity.

Solar energy is a primary source of energy that drives other processes, but it is not classified as a form of oceanic energy itself, unlike tidal, wave, or thermal energy.

Ocean energy can be harnessed through various methods, including thermal gradients (OTE), tidal movements, and wave energy.

Oceans cover approximately 71 percent of the Earth's surface and act as a vast collector of solar energy, which is stored as heat in the surface waters.